Analysis of potentiostatic current transients at metal/liquid interfaces: resolving the effects of a finite step interval

Potentiostatic current transients are used routinely for electrochemical analysis of metal/liquid interfaces. These measurements can be affected by both the electrochemical cell and the potentiostat used for such experiments. We demonstrate this in the present report with double-layer charging experiments using a gold electrode in aqueous electrolytes of NaF and NaNO3. By employing a high-resolution potentiostat, we show that the apparently instantaneous voltage step actually has a finite temporal width. The double-layer charging current develops an additional feature due to this behavior of the voltage step. We present a theoretical framework to resolve these instrumental effects from the actual electrical response of the double layer. The results are compared with a set of independent measurements of the same quantities using impedance spectroscopy. Copyright (C) 2001 John Wiley & Sons, Ltd.